The present invention relates to a process for manufacturing an insulating fibrous piece and also to the insulating fibrous pieces obtained according to this process.
It is well known to line enclosures intended to be taken to high temperature with a layer of an insulating material. To this end, refractory bricks were originally used. This technique, although wide-spread, presents the drawback of being expensive, of leading to heavy linings, sensitive to thermal shocks and which, for certain applications, have a high calorific capacity and a high thermal inertia.
For some years, it has been proposed to replace the bricks by fibrous sheets. In a first embodiment, it has been suggested to unwind on the wall to be lined sheets based on fibers resisting high temperature, such as ceramic fibers. These sheets are fixed parallel to the walls of the furnace by means of metal rods. These rods provoke thermal bridges, are corroded and precipitate corrosion of the walls of the furnace itself, and the fall of the sheets.
To avoid these drawbacks, in a second embodiment, it has been suggested to employ a stack of elementary sheets of fibers resisting high temperature, superposed edgewise or folded, fixed on the walls at the rear, which avoids the thermal bridges. This latter technique makes it possible only to effect a homogeneous insulation from the hot face to the cold face, which unnecessarily increases the cost thereof.
British Pat. No. 1 296 681 has suggested stacking successive layers of ceramic fibers on a form by means of vacuum. In this way, a progressive stack is obtained in which the elementary layers do not interpenetrate and of which the practical thickness is limited further to the technique of laying by suction.